Disclaimer: Harry Potter and Naruto do not belong to me. Honestly, it/they would be an odd series if they did.
I've been told Sasuke is a bit on the OOC-side, so forgive me for that. I have problems with excessive angst.
"A ninja's secret weapon… should be employed judiciously, not displayed at random to every foe you face!"
It wasn't enough.
It wasn't enough.
It was never enough.
Uchiha Sasuke dragged his aching, battered body into an upright position, feeling the acrid burn of that oh-so-familiar cocktail of hate, fury, guilt, shame, and despair rising in his chest. His cursed seal sent out jagged waves of dark chakra in response, but he forced it back, knowing it would only exacerbate his condition. The blasted thing was worthless anyway.
Everything was worthless.
Everything he knew, Itachi knew.
Everything he did, Itachi did better.
And despite everything he had, Itachi had more.
Damn you, Itachi. Damn you to fucking hell.
I will kill you.
Sasuke laughed. It was becoming increasingly easy to laugh at himself. Yeah, he swore to kill Itachi. He swore to get revenge. He sacrificed everything he had striven for, nearly killed his best friend, and submitted to the pawing and cackling of a madman out for his body, all for the power to kill his brother.
All for nothing.
There was nothing Orochimaru could give him that would help. Itachi, as just proved, would anticipate it and counter it, or worse, copy it and use it against him, growing even more powerful and harder to defeat. He needed something Itachi couldn't copy, couldn't use, couldn't counter, and couldn't anticipate.
He needed a trump card.
Sasuke wondered if something of the like actually existed.
It was hopeless.
Doomed from the start, even.
Harry collapsed into a cot the Room supplied, every muscle in his body sore, aching with tiredness, and trembling from exhaustion. Magical exhaustion was something he had little experience with; though it hardly came up in class, where concentration and control were key, his magical stamina was enough to leave him hardly fazed when his peers had cast themselves into unconsciousness. It was why it could be called Voldemort's equal, even though he really wasn't.
Magic wasn't like a muscle. A wizard was born with all he would have.
In stamina, he and Voldemort were matched.
In knowledge? In experience?
Hell, the aforementioned concentration and control?
I'm completely screwed.
All Harry had was luck, creativity, and gut instinct.
Harry wanted to laugh, because in dueling, those were the most important things to have. Knowledge could be gained. Experience could be won. Skill and control came with practice. Concentration merely took determination, something else he had in spades. He wasn't being arrogant when he said that he had the makings of a master duelist. He had all the basics. All he needed was time.
He didn't have time.
Even if he did, there was nothing he could learn Voldemort didn't already know. Voldemort was already a master duelist; there was little magic, offensive or defensive, he didn't already know inside and out, and despite his contempt of Muggle technology and weaponry, he was smart enough to eliminate that as a potential threat, as well. To effectively battle Voldemort, Harry would need something completely alien.
A power the dark lord didn't know.
The problem was, Harry didn't know it either.
They met in the Room of Requirement. Harry fell asleep there, but they never figured out how Sasuke got there.
Neither of them really cared.
The meeting was less than civil. They weren't interested in sharing conversation, but they did share hair-trigger tempers and the inclination to fight first and ask questions later. In fact, within a minute, there was blood on the floor. Harry was dead certain he would have been… well, dead if he hadn't been able to Apparate. Sasuke would have been dead if Harry had a shinobi's mindset.
Harry took a blade in the shoulder and Sasuke took a Body-bind in the back.
It was a while before they stopped to consider the implications of a magic-less boy who could make lightning and another that used space-time manipulation who had absolutely no chakra.
After that, they didn't attack each other when they happened to meet. They stepped around each other carefully, watching for anything that would give away the source of the other's unexpected power. Harry wondered if this was the way the Room meant to fulfill his desire for a chance against Voldemort. Sasuke just wondered what the hell was going on, and what he could get out of it.
"Who are you?"
"It's only polite to introduce yourself before asking for someone's name."
Harry arched a brow, privately wondering what rock this guy lived under. "Harry Potter."
Sasuke mentally did the same, wondering what kind of name 'Potter' was. "Uchiha Sasuke."
It was an accident of culture that had them both calling each other by their personal names.
Sasuke took tense quietude much better than Harry did.
"This is boring…"
"I have better things I could be doing that engaging in a glaring contest."
"I ought to be training, not sitting here…"
Harry sighed explosively, animated a dueling dummy and proceeded to bludgeon it to relieve stress. Sasuke attempted to discretely copy the strange techniques with his Sharingan, only to feel a sinking pit in his stomach when he failed to even copy the hand waves that were Harry's counterpoint to hand seals. Sharingan could copy anything. It could even copy bloodline jutsu, even if he couldn't use them.
But it couldn't copy Harry. It made him furious, until he realized.
This was exactly what he needed.
If he couldn't copy it, Itachi couldn't either.
There were only two problems with this miraculous solution. One, the ability was like a bloodline limit, whether it truly was one or not. Sasuke was confident he could get around that; it was about time Orochimaru proved a modicum of usefulness. Two, having the ability wouldn't mean anything if he wasn't able to use it effectively. To do that, he needed Harry's cooperation, and that was a kicker. Genjutsu were useless when your target had no chakra to manipulate.
He doubted any genjutsu masters ever took into account the possibility of meeting an enemy with no chakra. After all, everything alive had chakra.
Harry didn't. Sasuke tried hard not to think about that.
Harry didn't look dead to him, and if he was, that would really put a wrench in Sasuke's plans.
Harry hated being stared at. At the Dursleys it had been because a stare was his warning sign that Dudley's gang were up for a round of Harry Hunting. At Hogwarts it was because he was the Boy Who Lived, part-time hero and part-time lunatic dark wizard. Now Sasuke was eyeing him like a piece of meat, and it more than annoyed him, it was really creeping him out.
He also had a thing against red eyes. Sasuke was staring at him with red eyes.
"There's watching and there's staring like an idiot," he said. "Do you mind?"
The red eyes faded to black, and the look in them was calculating.
"Just curious about that ability of yours."
Harry's eyebrows went up. More than just curious, if that expression was anything to go by. "You're not the only one curious," he admitted. The bite of steel, two murmured words, and a flash of agony comparable to the Cruciatus… Only, he knew how the Cruciatus worked, and it wasn't by conjuring lightning.
Lightning could fry your brain a hell of a lot more quickly than a measly Cruciatus Curse, for one.
"I'll tell you mine if you'll tell me yours," Harry offered.
Sasuke had no magic. His powers weren't remotely magical in nature, although they would still fall under the Muggle description. That meant, as things were, Harry couldn't use them, but there were ways around those limitations.
Ways that he might mention, if Sasuke's ability sounded useful enough.
Harry didn't generally think like this, but there was a war going on out there.
And there is a man I have to kill.
The truth was Sasuke felt apprehensive, not that he would ever admit it. Nor did it show on his face or in his posture as he knelt down in the circle of runes Harry had spent the last few hours painstakingly transcribing. He didn't know much in the way of fuinjutsu, but the lines and graceful arcs reminded him of the sealing art.
"It's mostly intent-based," said Harry, crouching down in his own circle. "Magic is mostly about intent. If you want something badly enough, it will happen… just not always how you expect."
Harry smiled. It was that thin grim smile that told Sasuke the other was milking their situation just as much as he was. "Stop thinking it's going to mess up. Because I will make this work."
They both wanted it badly enough. Perhaps they wanted it too much.
Magic felt like lightning coursing forever just underneath his skin. It was like caffeine, and channeling it gave Sasuke a kick not even the curse seal's dark chakra could match.
Chakra was different, like cool rivers that flowed through his veins in place of blood. It was oddly exhilarating to be able to exhaust himself, and Harry found the realization that doing so only made him stronger was more gratifying than anything magical he had ever done.
But that wasn't all.
Sasuke nearly shocked the piss out of Orochimaru when a spar and a summoning led to Sasuke turning his own snakes against him. It wouldn't have been troubling, as they had both signed the contract, except that the snakes in question despised Sasuke and never obeyed his commands.
But in the face of what Harry called Parseltongue, it was impossible for them not to.
Harry terrified the hell out of several Death Eaters when an attack on Hogsmeade led by Bellatrix Lestrange threatened the lives of Ron, Hermione, and him. Everything seemed to slow down, taking on an unearthly clarity that belied his broken glasses, and before he knew it, they were all down.
What Sasuke called the Sharingan, altered by magic, was his enemies' worst nightmare.
Sasuke looked at Itachi, a thin smirk on his lips.
His brother was talking, but he didn't hear.
"I promised I'd kill you," he whispered.
Itachi looked at him, opened his mouth to reply-
-and collapsed to the floor, trapped in a body-bind.
The utterly baffled non-expression on his older brother's face made him want to laugh, and since Sasuke didn't mind laughing anymore, that was what he did. Then he took out a kunai, and fulfilled his main ambition.
Harry looked at Voldemort, half-smiling.
The madman was preaching, like he usually did.
"Neither can live while the other survives," he murmured to himself.
Voldemort raised his wand, ready to kill-
-and jerked when the sword of Gryffindor bit into his shoulder. Lightning chakra flowed down the blade, and he collapsed, screaming.
Harry didn't let up until his enemy was nothing more than a twitching mess of limbs. Dismissing the clone that Voldemort had held captive, he picked up the slim piece of wood he had replaced with and turned it over in his hand. Then he aimed it carefully, and fulfilled his prophecy.
Trump card: a highly valuable resource or advantage, usually held in reserve for future use.
Comments, questions, and criticism welcome. Thanks for reading!